[Username Protected]

I'm a new Phenom 100 owner/pilot.

What's normal in terms of Emergency Brake Accumulator Pressure? I parked the plane for about 30 hours and when I started back up the EMER BRK ACCU PRES had dropped to 2200 PSI.  The brake was not engaged during this time (parked on the ramp with chocks).

Parking for longer (like periods of 6-8 days), I've seen it drop to ~1500 PSI, and in those cases I used a GPU to top it up. But now I'm wondering if even that is normal.

Is this a maintenance issue? What should I be expecting on this?

[Username Protected]

I'm a new Phenom 100 owner/pilot.

What's normal in terms of Emergency Brake Accumulator Pressure? I parked the plane for about 30 hours and when I started back up the EMER BRK ACCU PRES had dropped to 2200 PSI.  The brake was not engaged during this time (parked on the ramp with chocks).

Parking for longer (like periods of 6-8 days), I've seen it drop to ~1500 PSI, and in those cases I used a GPU to top it up. But now I'm wondering if even that is normal.

Is this a maintenance issue? What should I be expecting on this?

The e-brake system pressure will slowly leak down to the accumulator nitrogen pressure (what you are suppose to check every 15 days) and will do so faster if the parking brake is applied. 1500psi doesn't sound too bad, perhaps a bit low depending on the temperature; look at the chart in the POH. When you plug in a GPU or start an engine the pump will kick on and re-pressurize the e-brake circuit, this is normal. The circuit is isolated from the main brake hydraulics by a check valve; however, even the best check valve will slowly leak over time. If you see the e-brake pressure decay during a flight that is not normal. Typically, you should only hear the hydraulic pump kick on once if at all during a 2-3 hour flight; it is noticeable. I typically do not leave the parking brake engaged while parked for an extended period of time; carry a set of chocks, that way you should have e-brake pressure during startup.

[Username Protected]

Hi (Username Protected),

Have you performed the Hydraulic System Check to check the Emer/Parking Brake nitrogen pre-charge? The pre-charge is usually serviced to ~1550psi. If the pre-charge is low, the accumulator will have a difficult time holding pressure. Procedure attached.

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[Username Protected]

Here's an update: Mesa got this figured out for me. It was a leak at the brake itself.

The Nitrogen pre-charge was fine (and I did do the check).

It's now holding great, and I'm glad I checked.

[Username Protected]

Awesome! Glad they figured it out. I'm constantly chasing leaks in the brake system.

[Username Protected]

Great info guys….how long does your main hydraulic pressure stay charged between flights? I came back a day later and main hydraulic pressure was zero until I hooked up gpu. Seems like it used to last a week or so before pressure bled off…thx.

[Username Protected]

I have no issue even after a week, in green…

[Username Protected]

(Username Protected)-

That’s normal for all the 100s I’ve ever flown. Within 24 hrs hydraulic (not EPB) pressure has bled off.

Great info guys….how long does your main hydraulic pressure stay charged between flights? I came back a day later and main hydraulic pressure was zero until I hooked up gpu. Seems like it used to last a week or so before pressure bled off…thx.

[Username Protected]

Also,

I would suggest using leak-tec solution to find out if there are air leaks around or at the schrader valve port, usually located at the end of the accumulator or in the vicinity. These have o-rings and they wear out or they just start leaking. I have also seen the nitrogen charge pressure gauge have internal leaks, you might want to spray some leak-tec around it.